Sandman was Raimi's idea
the one-armed guy that you see in the first 2 (peter parker's college proffessor) was going to try to grow his missing arm back and turn himself into the person-sized lizard in the 5th movie of sony's 6 picture deal, that's what sony wanted, that's the whole freaking reason the one armed guy is in the first 2 movies to begin with, and the one armed guy being pete's college proffessor was going to be used to explain why spiderman is the person who stops the lizard's rampage, as opposed to any other superpowered hero, when sony signed the 6-picture deal with marvel, they were going to limit themselves to just 1 supervillian per movie, with norman osborn being the first goblin in the 1st move, doctor octopus in the 2nd movie, harry becoming the second goblin for the 3rd movie, venom in the 4th movie, the one-armed guy turning into the lizard in the 5th movie and the last movie being carnage, when Marvel gave Sony permission to use multiple villians in one movie, they wrote the lizard into the 3rd movie instead of the 5th, with a big fight scene where the lizard and venom are trying to kill each other, Raimi changed the lizard into Sandman at the last possible second, Sony let him do it, cuz they still had 3 more movies they could fit lizard into, Sony then wrote a huge special effect, lengthy scene of Sandman and Venom trying to kill each other, but Raimi said he wouldn't film that, then Raimi inserted the whole Sandman's backstory into the movie, and that's why Sony fired him from the franchise, Sony's putting Lizard into this re-boot because they had already planned on having the lizard in a spiderman movie all the way back when they put the one armed guy in the background of the very first spiderman movie