Post the verses where YHWH explicitly instructs Abel to perform animal sacrifices. OR did he just do it on his own???
I didn't say G-d told Abel to offer animals. I don't claim to be able to find any such verses (though perhaps the Oral Torah contains this information). All I said was that Ramban disagreed with Rambam's claim that Judaism adopted animal sacrifices from the pagan religions surrounding them because Abel offered animal sacrifices long before paganism existed (assuming you accept the early chapters of Genesis as real history, as I do). However, the verses which state that G-d accepted Abel's animal sacrifices but not Cain's vegetable sacrifices are right there in the story.
I simply don't understand why so many people want to reinvent the wheel. The definitive Jewish/Noachide religion comes from Sinai and is contained in the authentic Rabbinic Tradition. To stubbornly refuse to see this, to insist on inventing new stuff right out of the air--by combining Judaism with chr*stianity, G-d forbid, or rejecting the Oral Torah, G-d forbid, to make a more modern, academy-friendly religion--simply seems to me a huge waste of time (not to mention an act of stubborn rebellion against G-d).
If you believe the Prophets have greater authority and authenticity than the Torah, then you're way around the bend.