Question re: John 3:16

Full disclosure, I'm Jewish/agnostic. I also have a special interest in Christian theology, particularly the weirder/heretical types, so I'm in a fairly iffy place to assess these things (I know a fair bit, but I'm also inherently skeptical/may have missed some mainstream things in favor of heresies.)

I've always struggled to understand the import of this verse/concept and I'd love to hear from people for whom it clearly means a lot:

Jesus \*is\* the Christian god according to mainstream Christian theology. Additionally, said god is omnipotent.

Given that... why is it such a big deal for said god to have given "his only begotten son" (slash himself) to die? It seems to me he could've had more kids or dealt with sin/redemption another way if he wanted, so it's not a huge deal for a being that can create universes. What are the teachings about this/why it's such a big deal/display of love?

Also, I'd like to think that if I was offered the chance to spare all of humanity from eternal suffering in exchange for being tortured to death (but resurrected shortly thereafter,) I'd agree. Obviously I don't know if I'd actually \*do it\*, but what makes Jesus's sacrifice so special? The fact that he was god and didn't have to, or something else?

Last thing, and apologies if I don't need to say this, I've just had bad experiences (both personally and ancestral trauma) - I'm not looking for any kind of argument for conversion, I'm just curious about the theology behind all this. I'd like answers to "why do Christians believe X" rather than "why should I believe X," so to speak.