Literally everything you wrote here is false
Have you actually watched football at that period? You didn’t sound like you did.
Messi:
At 17-18: 1 goals in 9 games
At 18-19: 8 goals in 25 games
Mbappe is clearly better. Far more established but arguably less talented. He already shined in WC and CL at that age, whereas Messi is mostly only a bench player in Barca, although he is regarded very talented youngster with huge potential, but potential and raw talent is just, potential and raw talent. He did nothing at that age to suggest he is already better than Mbappe yet. You would be the most bias person in the world if you think otherwise.
Messi:
At 19-20: 17 goals in 36 games
At 20-21: 16 goals in 40 games
Mbappe and Messi are more or less equal in objective sense, although Mbappe is more productive in worser league, Messi has edge on superior performance level. In terms of pure subjective sense, you may favours Messi more as he is clearly better dribbler and capable of scoring some wonder goals. But Mbappe does have far better output season over season. At 20 Messi finished top 3 in Ballon D’or, Mbappe finished top 4. So it’s matter of subjective preference.
Messi at 21-22: 38 goals in 51 games
Messi is clearly far better in terms of performances, although he is at similar productive level as Mbappe, he did it in far better league. Messi also won Ballon D’or first time at age 22. No question Messi is far better at this age.
So every part of above is wrong according to you? Like seriously? How old are you actually? Are your merely a thick person or just a heavily biased person?