he played there for arsenal, played there for barca, he even played wide on the right for france in younger days and featured there for Juve
he's pretty much always been a wide forward coming in mainly from the left, similar to Salah but other side and like Salah not so much focus on defensive duties (unlike a Mane who has slightly more defensive duty)
this is nonsense and you know it
I don't know if you're too young to have watched him play at his peak, but he really really hasn't 'always been a wide forward'. You have it the wrong way round.
Quoting his Juve days is grasping at straws at best as he was mostly considered a flop playing in the exact position you have him in. It was at Arsenal where Wenger moved him off the left and played him at centre forward, allowing him the freedom to drift to the left and score goals from all over the shop, but focusing all his play down the middle. That's where he played his best football over this period. His best form was also alongside an SS or creative 10 for Arsenal and France - see Bergkamp and Zidane. Van Persie was an odd pick to make, as neither really formed that much of a partnership together at the time. Wenger rightfully had Henry as the main man at CF with Van Persie coming off the bench or occasionally the two up top, him chipping in the odd goal where he could. If anything you should be pushing Van Persie wide to accommodate a far superior striker in Henry.
Salah and Henry are very very different players. Maybe similar on the surface, but Salah cannot hold a front line the way Henry could. Henry was an infinitely better goalscorer than Salah as well to be quite honest. Far more consistent too. The man was an absolute machine at his peak and you shunting him off to the left is a waste. Like I say, he can play off the left (he mostly did at Barca - though I'm only judging players on their time in England), but that not his best position. Saying otherwise is simply untrue. You should be focusing your whole attack on your best player.
France fan here who watched his debut in blue and has followed his career ever since. Probably one of my favourite non-Liverpool players ever.