Haunting Ground's original scenario draft was written by Noboru Sugimura, the similarities to BIOHAZARD aren't a fluke. The setting, Fiona and Hewie were both reused from the scrapped Castle version of BIO4.
Spencer was not featured in that game so it's doubtful Lorenzo has any connection to him, but Sugimura probably wrote Lorenzo based on how he envisioned Spencer in his head.
Spencer was originally going to be a monster in the version of BIO4 that became Devil May Cry. He was initially superhuman, an adapter to the Progenitor Virus, who then administered it to his twin sons. He would've used the G-Virus and become a transfigured God, only to be killed and replaced as Umbrella CEO by his son Dante.
Spencer's final depiction is pretty much perfect. It's not grandiose and it shouldn't be.
Spencer is grounded well for his role, and he does work better being someone we see briefly, and how he's depicted works with everything else we know about him. More-so, going from Lost in Nightmares, you do see more of his reasoning and lead-up to that encounter as a lot of the DLC story is to really build of Spencer's final moments and a bit more of who he was behind the scenes, both from his final plea for life and his personal butler's impression of him. There wasn't any room in RE5 as it was for an over-the-top Spencer. But I do admit I someday want to see the sort of RE villain who goes over-the-top in personality twistedness rather than monster transformations. It's definitely been toyed around with, between Alfred/Alexia, Simmons, and Alex post-infected most recently. But it'd be interesting to see how it plays out.
I know some of the Resident Evil/Haunting Grounds relations, but I do think the similarities between Lorenzo and Ozwell's final depiction are more coincidental than intentional (unlike, say, Uroboros, who no one can convince me wasn't at least slightly based off of the very similar looking tentacle monster in RE3.5). There are definitely Haunting Ground plot points that scream Resident Evil inspiration in them, and while Haunting Ground takes place in a European Castle that may explain some setting similarities, there are certain rooms in Haunting Ground that unmistakably bear a similarity to scrapped rooms seen in early footage of RE4, and all the observations one can make. While Haunting Ground follows Clock Tower 3's footsteps, it definitely has more of a Resident Evil flavor than CT3 or any of the CT games, which I always found fascinating about the game. It's like a weird cocktail if you were to take Clock Tower 3 (specifically since Haunting Grounds' core gameplay originates from it), then blend it through weird Resident Evil vibes (gameplay similarities, early RE4 similarities, focusing more of pseudo-science (of alchemy & cloning mostly in this case), and there's just a more RE feel in general one could dig into with how its designed) mixed with stronger Giallo horror tones like the original Clock Tower, and added exploitist horror tones.
So how many capcom games owe their existence to Resident Evil? In terms of a potential RE game becoming a new IP.
Well, got to start at the root, Resident Evil originally was supposed to be a remake of Sweet Home, so even RE was spun-off of an existing Capcom thing.
Devil May Cry is the obvious one. Dino Crisis would be another big one. Haunting Ground definitely pulled some stuff away from RE. I don't know what level of inspiration Resident Evil had on Dead Rising actually, though you feel there's got to be something there (despite RE and DR not being all THAT similar, they differentiated them pretty well, even though Dead Rising: Drop Till You Drop specifically owes a lot to the RE4 Wii). Lost Planet 2 has definite Resident Evil 5 inspiration behind it.
I'm sure there's more than we know or will be listed, but Devil May Cry, Dino Crisis, and Haunting Ground would be the obvious ones.
And obviously outside of Capcom, a lot of horror games owe a lot to RE.