re. Henry vs Mbappe, I don't think that's a closed debate or an easy win for Henry, not even close.
Henry's performances, his best ones, were on a lower stage than Mbappe's have been. Mbappe has proven to be a true big game player; Henry was dogged with 'bottler' tags for practically his whole career. When the stage was massive and all eyes were on Henry, he rarely gave his best performances, certainly not like Mbappe has, where the latter seems to thrive in the spotlight and wants the ball as much as possible. Mbappe also plays the big games with a smile on his face and is with the audience in terms of the melodrama; Henry played most big games as if he knew it was defining him and his career, with a grimace and a discomfort.
And when I say 'big games' we're talking CL and country, not domestic football, where Henry was almost peerless and was in his element, which, ironically, had more people question why it wasn't transferable.
Lastly, Mbappe doesn't defer to anyone; even if he had fielded with a Zidane or Platini, he would have the ego to believe he was on par (or better) than them. Henry's deferential nature to Zidane had him play as a supporting member rather than believing he could claim the centre stage. Mbappe would be vying for that centre stage, not wilting for another in it. These things are huge at the level we're talking about.
As players, Henry was at a higher technical level than Mbappe, but he wasn't more effective. Again, at the highest levels, not domestic football, where Henry's goal and assist ratios were extraordinary. Head-to-head, Henry is not getting in a France team over Mbappe because the latter is more decisive and more likely to be the player who turns the game.
To be able to say this of a 23-year old over a player who has a full body of work says a lot, too. Mbappe has played two World Cups and has looked like he is in element, twice. It's not a coincidence; he clearly has the it factor and it's injury that will curtail him, not nerves or fear of any game or opponent. Domestically, Mbappe can catch Henry, on higher levels, he has already surpassed him.
When it comes to 'ever' he's levels below Platini at the moment and will have to really turn godly to peer with him, let alone surpass him. He's also got a way to go to be as consummate as Zidane and will have to become the main man at his club(s) and country (he's certainly as important for his nation as Zidane was, but needs longevity to par him) to sit alongside him. There isn't really another French attacker he hasn't hopped over by now, so he is certainly the player who has it in him to go to the very top, if fitness and will to improve is married to sublime football from here to the end of his 20's, at least. I don't think it'd be a surprise if he ended up being the #1 should stars align for him, it's not something that's risible as he has the ability, ego and confidence to go all the way to the top.