Pretty sure that HE canonically started his career in the 1930s (and gave some tutelage to one Miles Warren). Just because he debuted after the Lizard doesn't mean he wasn't active off-panel before then. It's an odd arguement to make given we're discussing a character who literally debuted in the last issue.
And my point isn't that HE should have been the inspiration for the Lizard. Nobody should be the inspiration for the Lizard! The tragedy of Curt Connor's story is one of (albeit well-intentioned) hubris, saying it was someone else who secretly sabotaged it all along detracts from the themes of the character. Ditto Morbius.
Plus Madame Monstrosity maybe doesn't understand the scientific method? Unless Connors, Morbius, and everyone else was literally burgling her lab (which would raise the question of how nobody knows who she is) how could they have stolen her work unless she wrote it down somewhere it could be found?
Like, Essex wrote his theories down before he full on became Mr. Sinister (and I guess a few other people...) and that's what inspired the HE, and near as I can tell there was no grudge there. And then as mentioned the Jackal learnt from him. If she kept her methods totally secret she officially forfeits literally any right to someone else indepedently figuring out her own theories. Now she's a villain so her having a sense of possession over someone 'copying' her (despite having indepedently arrived at similar conclusions) is something I can see, but again you kind of have this situation where you've undercut the underlying themes of these other characters by wedging her into their backstories.