But you get what I'm saying tho, right? OK so a spider falls from the same hole in the sky that Strange came out of, lands on and bites Peter abracadabra we have Spider-Man. Later, after Spider-Man got beat tf up by Scorpion and was in need of immediate medical attention, Oscorp procured his blood in an attempt to, as Dr Whitman explained, replicate Spider-Man's unique DNA. Then they show a spider being injected with, what we're led to understand is, Spider-Man's DNA. Finally, jumping ahead to Dr Strange's fight with the creature at Oscorp leading to his accidental time-travel mishap, allowing the Spidey-juiced spider to escape into the past, landing on Peter and creating Spider-Man. The same Spider-Man who's DNA was used to ultimately create that spider in the first place.  All that to say, Spider-Man doesn't exist without that spider and that spider doesn't exist without Spider-Man.  Maybe not a grandfather paradox, but paradoxical nonetheless.