Keep persisting on offering a variety of foods. Don't always offer his favourite things as he'll gravitate towards them instantly and be less likely to eat the other foods offered. Have you tried adding bananas/berries to things like yogurt, weetbix, porridge to introduce a new flavour with something you know he likes? Try making things like banana bread, fruit muffins, berry panckaes etc. to bring in new textures and other flavours/ingredients. He may want to explore food more with some cutlery. We got a little set of munchkin forks and spoons from amazon for about £4.50, they're plastic and curved, so safe and easier on LOs hands and my LB loves using them to eat x
Have you tried to give him cutlery? Maybe picking up proper food with his hands isnt appealing