Quite a decent percentage of our legends and very good players when they were 21 would have been shown up by an 18 year old Harvey Elliott. Elliott is a very impressive 18 year old. He is not in the Gerrard, Owen, Fowler bracket whose talent screamed "play me every game" when they were 18, but definitely in the tier below that.
But youngsters develop very nonlinearly. Just because Elliot at 18 looks a couple of tiers above Henderson at 20, doesnt guarantee Elliott at 28 will be as important as Henderson at 28.
Jones is a tier or two below Elliott and that is not a bad place to be. Plenty of very good to great PL players were in the Jones's tier or below that when they were 18-20.
Jones has shown in the past that he belongs in a PL midfield. He is now being asked to curb his natural instinct and play a different game. It will take time for a youngster to learn how to do that. It took the great Thiago more than a season to become an integral part of this midfield. There are a lot of positive aspects to Jones's game. He has the confidence. He can dribble and take the ball into dangerous areas. The sort of thing we bought Keita for before his untimely death (RIP). He has good shot taking ability - capable of the spectacular. Worst case, he develops into a MOTD player who does something spectacular every few weeks. It is worth persisting with him as there will be plenty of clubs willing to pay top money for a English MOTD player.
I think the biggest problem with Jones is that his whole demeanor is kind of unlikable. I suspect that is why criticism of him is a bit on the harsher side. He scored a brilliant winner against Everton which made T-Rex hands look like a chump in a FA cup knockout game. And we all know it is not a one off and he is capable of more such goals. So definitely worth persisting with him. At the very least, he will rise to a Ox or Lallana level talent.