Genesis is the first book of the Bible, one of the five books in the Pentateuch, the first of the books of Moses.
It's an epic narrative that follows a family line with lots of genealogies and a focus on geography. There's a global story being told but its constructed by localised family stories about marriages and childbirths and the threats and opportunities as families collide.
1-11 From Adam to Babel via Noah.
12-25 From Abraham to Isaac.
26-36 Isaac's sons, Jacob and Esau. Jacob is a deceiver trophy of grace.
37-50 Jacob's sons, Israel - centred on Joseph. Joseph is a picture of Jesus in remarkable detail, even though Jesus comes from Joseph's treacherous brother Judah.
Structurally the phrase "these are the generations of" marks out sections and sub-sections - or Acts and Scenes in the story.
The goodness of the Triune God forms and fills the world, creating a good world - but humanity quickly betrays their Maker and Husband, the LORD. The LORD enters into the garden to search for his hiding people, a betrayed lover asking "where are you?" Curse replaces blessing and the stage is set for a great drama: the woman will have an offspring, so will the deceptive serpent.. the serpent will strike but will be crushed... will it be Abel vs. Cain.... Abraham vs. the Pharaoh... Jacob vs. Esau...
It's worth watching the three events around a man lying about whether his wife is his sister - with Abraham twice, and with Jacob. Famine strikes and the man finds himself in the territory of another. He lies to his host - assuming him to be a villainous tyrant (a serpent). The first, a Pharaoh is a tyrant and Abraham does well to deceive him. But Abimelech (twice) certainly isn't... he's a godly man. The repetition isn't bad editing but there for a reason... There's also two trips to Egypt... the first with Abraham and then with Joseph - again both times in famine... the first sees Abraham have to deceive the Pharaoh, second time around Pharaoh makes a seed of Abraham his right hand man... and things turn out very differently.
The plot-line follows a search for the seed who will defeat the serpent's seed and bring his people back into the fellowship of Eden. Geographically we begin in Eden, moving eastward before the flood, then to the plains of Babylon and then to Canaan before the story ends not in Eden (the land promised to Abraham's Offspring) but in Egypt with great favour (that will transition to slavery by Exodus).
The question sharpens as we consider Noah, and then Abraham's promised son Isaac, and then onward to Jacob and seemingly to Joseph - though the legacy beyond his generation seems to lie more with Judah "from whom the sceptre will not depart" and Levi, from whom Moses the central human figure of Exodus comes. The New Testament makes explicit that Jesus is this seed.
We also see 'The Word of the LORD' walking in the garden, the Angel of the LORD who meets with Hagar, the Word of the LORD who leads Abraham outside and is believed in, the LORD on earth who eats with Abraham and cals down fire from the LORD in heaven, the LORD who wrestles with Jacob. This is not the Incarnate Israelite Jesus, but it seems to be a walking, eating divine person - surely the same Second Person of the Triune LORD present with his people, not permanently but turning up at significant moments and being called upon by many.
Salvation, in the terms of Romans 10 by "calling upon the name of the LORD" is Genesisian... salvation by being counted righteous by faith is Genesisian - Noah and Abraham are righteous... the worship of Abel is accepted as by faith. These are not primative people but perhaps more rightly should be called the earliest church fathers. The foundations of the gospel are laid in Genesis.
A controversial opening?
Genesis inevitably prompts questions about the origin of the world vs. modern scientific theories. This tends to circle around a) the age of the earth - which could be as little as 6400 years if you add up the genealogies (Abraham lived around 1800BC)... b) whether Genesis 1 is a literal account of the creation of the world in one week.
Christians differ on how they read Genesis 1 and there is room for interpretation here. What's certain is that it's a very structured account of creation that emphasises a theme of forming and filling what is formless and unfilled, as the goodness of God spreads into his creation. The non-negotiable is that God is the creator - we're warned in 2 Peter that those who don't believe God created the world or deluged it at the flood will inevitably not believe in his final judgement. Get the big stones in place and then move to the details.... also note that Genesis 1 wasn't written to engage with modern scientific debates, it's literature that isn't designed to answer those questions. Some think it's written to interact with other theories of creation in the ancient world, but perhaps it's mostly a revelation of the God we know when we know Jesus...
Whilst there are issues at stake in Genesis 1 there is probably more to say "theologically" about needing to believe in Adam in Genesis 2-3, because the Bible portrays him as the head of the human race, leading us to death in the same way that Jesus is a second Adam who leads us into life... if Adam wasn't real it's hard to hold to a real Jesus...
Other issues in Genesis?
Polygamy seems common in the world of Genesis, but as you read ask whether it turns out well for people or not? Because the patriarchs (as they're called... the fathers of the nation) did things that doesn't mean that they're being endorsed. Abraham lying to Pharaoh and Abimelech... is he faithless or is he deceiving a perceived enemy? Is Abraham asked to practice child sacrifice in Genesis 22 -- or are we given a picture of what our Father in heaven will do for us as Jesus dies as a "burnt offering" on the slopes of the same mountain in Moriah...
Genesis is an epic adventure. If you read 10 chapters a day you can finish it in five days, or perhaps take it in four and follow the four main Acts of the storyline outlined above... rejoice that the Seed of Abraham has come, that God's grace has triumphed and villains and fools like us can walk with God.