Just wondering also i meant to put figure out

Adam and Eve had perfect, unmutated genetic bodies. 3 offspring were named but they had other sons and daughters per Genesis 5:4. Starting with perfect genetics, intermarrying wouldn't have caused many negative anomalies early on. Those that weren't named were outside the genealogy to Abraham and beyond( males) or women who overall were rarely named.

Adam and Eve had more children and then after that those children had more children and when Moses came around. God commanded them to stop having babies with their family members. Hopefully that makes sense.

Yep

My theory is that God created other people outside the Garden after Adam and Eve fell to temptation.

Can't go with that personally.. on the seventh day, God rested from creating and Eve is said to have gotten her name from being the mother of all living.

But think about it, he would have had to, because when Cain was exiled he was worried about what other people would do to him, but the Bible only mentions Adam and Eve

Indeed. Would you be more worried by non family members or family members of the one you had killed? "That guy killed my brother" or "That guy killed someone I never met" and how would the non family and only recently created have found out?

“Cain replied to the Lord, “My punishment is too great for me to bear! You have banished me from the land and from your presence; you have made me a homeless wanderer. Anyone who finds me will kill me!””
‭‭Genesis‬ ‭4‬:‭13‬-‭14‬ ‭NLT‬‬

Not because of what he did, just because he’s a wanderer

Still there is no need for other people groups for Cain to fear, although in his new mental state he probably feared everyone around him and he could not longer do that which he had always done which was farm. Science (secular not faith based) has declared there is a mitochondrial eve in our DNA. The ultimate matriarch of the human race. Science proves the Bible again, go figure right? That had to leave a bad taste in their mouth I'd guess. More proof of no new people groups introduced. God didn't need to introduce anyone else into the mix for violence to ensue. Man has mastered that all on their own. Cain is proof of that.

Yes but consider like bandits along the Silk Road, it wasn’t a “he killed his brother” situation just “let’s kill that guy who’s defenseless here all alone

Way too much of a stretch to be believable. But it shouldn't be something that will keep either of us from heaven so run with it if as long as you want

Perhaps it is. One day we will both be in his throne room and we’ll ask him in person

Indeed. I greatly look forward to meeting you there