No idea why Rashford isn't playing in this. All nations have their best young players playing, even if they have played for the main team. Renato Sanches is playing for Portugal, who played quite a few games in last years senior Euros win. Donnarumma is playing for Italy, with Bernardschi and Rugani who have all played with the senior team. Germany have plenty of youth players that have been in their senior squads.
Englands senior players are Ward Prowse, Chambers and Redmond. Who came on as subs in the Germany game a few months back. Rashford has played 1 game for the u21s, doesn't set him up well for playing interntional tournament football in the future.