This story is... Slowly falling apart.
Not because the story can't be interestingly constructed yet, there's a lot of points that are in theory interesting you can write from this point onward, the problem is...
Any continuation of the story I can think of is becoming less and less interesting that whatever could happen before this chapter.
Probably most interesting story progression would be mc struggling to end his secret experiments, someone finding out and then the whole story ends in him de facto becoming a mid-boss, but he made so much friends by changing due to reincarnating, that it evolves into some sort of civil war plotline.
Meanwhile we are going in the direction that ends with mc fighting with the Prince for entirely justifiable reasons... Where everyone will support him not cuz they like him, but because the prince is an asshole...
And wherever the story now goes, I don't think adding the idea of more reincarnators will be interesting in the slightest. I mean it adds interesting story points and maybe characters(which I don't think it will, cuz look at the mc) but the entire story doesn't really get much from it because...
THE ENTIRE PREMISE is that it's a game world with set story, and mc is navigating it to change the future. Entire point is that main character usually makes small changes, or changes no one will notice, because he stops major events from happening before they happen by doing small things. If you make a major character of that world change the entire story at the de facto still beggining, it is not a compeling story of this type anymore, it's just... a story that could hapen without game and isekai bits.