Theories make the game and discussions more interesting. Especially with this kind of game and how there's a lot going on. It's also enjoyable to hear and read other people's thoughts and how they interpreted certain scenes.
I have a few gigabrain takes that will most likely not happen but there's enough factors in game to support it in some way, currently. One of them is that the MC being "perfect" has to do with his ability having the potential to be an Authority that allows him to be peers with Numbered Monsters when he reaches Natural Evo Lvl 5. Basically being Independent from their system but gaining all the benefits and "glory" of/as a Numbered.
It goes further because it would explain why Ella wanted it bad enough, before evolving, that she'll kill the MC if he reveals he has this ability. She was also disappointed by confirming she really didn't have it after reaching lvl 5 artificially(this lvl is really important). There's more to the theory that goes into how Natural Evolution vs Artificial Evolution work. Some of which has some confirmed details(Natural > Artificial) but otherwise head canon.
We think Natural Evo isn't capped at lvl 5 vs Artificial, which has lvl 5 as the final. There's theories(my own) that once you cross a certain threshold with Artificial Evolution, you lose your path because you sever your connection/link to your Monster Parent too much or entirely, causing you to plateau. Said link is found within your soul or spirit. You learn about this link in game when you have high corruption during the Minyak scene.
You might say, "well, if that happens with the authority part above, involving the possibility of becoming a numbered monster or equals with them, why would the Monsters allow it to happen?". I would say because the process could be something that usually always fail in the end. So, from their perspective, they gain a very powerful spawn under them that they have full control over since it's via all Natural Evolutions. There's no guarantee that the power will become an "authority", just the possibility of it.
I could go further with it but it would take a lot of explaining(and I really do mean a lot). I would rather wait until after playing this update coming soon to give me a better picture that could further or dial back the theory. Again though, it's a theory and I don't see any of this being true but it's a fun thought to form from what's there in game.
Quite an interesting theory.
I also have one of my own.
I believe that the word "perfect" meant that MC can steal powers, which is the ultimate evolutionary ability. Let's not forget that she used this word only after we revealed to her that we had "borrowed" the abilities / characteristics of certain animals. In addition, we have proof that it works also on super humans, because we gained some powers of the guy who made zombies out of black slime.
Ella has very similar abilities to MC but there are significant differences. Ella can change her body without restriction and at will. Her starting point is much higher than the one MC had. Unfortunately, her body is also her limitation. Although she could turn into a snake, for example, she would not have poisonous teeth. Her current form would only change shape to snake. MC is able to turn into a full-fledged snake, which would be 100% the same as the original. Unfortunately, he is limited in that he would first need to find such a snake and touch it. So take the ability to make perfect copies (+ combine the characteristics of different copies) and the ability to copy / steal other people's power, and here you have something every superhuman would love to have.
I also believe that Ella has the ability to absorb dead superhumans. That's why she gives away so many pills and tries to make her "childrens" reach their full potential. But given her behavior, I conclude that she is only able to absorb your current level of power, and that absorbed power inside her no longer evolves. Therefore, she needs only strongest individuals with the most useful abilities.
And regarding Natural and Artificial Evolutions...
I believe that artificial evolution is just an improvement on your current abilities. Something like +200% to all current stats and abilities. But natural evolution is something completely different. Not only will you get a general power boost, but there will probably be some changes and/or new abilities. In addition, the change is much more personal and adapts to your needs.
P.S.
Serum for artificial evolution is most likely created by processing monsters.