a 1 year old throwing food on the floor doesn NOT mean they don't like it! Far from it!!
Good point! I didn't even think to comment on the throwing.
I keep putting it back on the high chair but then he just throws it again and so we continue.
I wouldn't put it back.
He understands a lot of what you say so here's what I would do. First when you offer some food you show him the food and say "this is for eating, do you want it?" If he puts his hand out to take it say "this food is for eating. If it goes on the floor it is gone. OK? Gone. If you don't want it, tidy up please."
Then let him take the food (if he doesn't take it then meal time is over). As he takes the food though stay vigilant. If he goes to throw/drop it over the edge of his chair get his hand or arm quickly (firm but gentle) and say firmly "either eat it or tidy up". Guide his hand back over a plate and tell him if he doesn't want to eat it then put it down and tidy up.
When mine was little "tidy up" meant putting all his left over bits into a bowl or plate (I mean collecting bits from around the tray) and then holding his hands for me to wipe before taking him out of his chair. I found it very helpful to put the food into a bowl/plate rather than leave it on the tray simply because you can then move the bowl right out of reach to another surface and he can't get anything to throw.
There is a chance you can even hold the bowl out as he goes to drop food over the side and say "tidy up please" and let the food drop into the bowl. This turns the negative action into a positive and you can say "lovely, and tidy, thank you!" then put the bowl aside and wipe his hands, offer a drink of water, take him out of his chair.
If food does make it to the floor because he somehow outwitted you leave it there and make no move to pick it up at all. If you pick it up it becomes a game. Leave all thrown bits on the floor, although tbh if he gets two pieces past you meal time is over. Take a deep breath and wipe him down calmly and move on with the day. I would only pick up food from the floor when my DS had left the chair and I'd put him in another room so he couldn't see.
Often at this age they get into the "fill and dump" game which can be helpful in teaching table manners to tidy up the tray at the end of a meal. But always get that bowl away after the "filling" unless you want the "dump" part!
You could also set up some activities during A time to fulfil the fill and dump need or to fulfil the mummy-reacts need. Rolling a ball to each other or him throwing a soft ball or pair of rolled up socks and you passing or throwing it back etc. Games which fulfil his desire for you to pick up and him to throw again. The "giving to receive" aspect is a great development for sharing and team work you just don't want it to be with food.
What most people find is that they need to end meal time much sooner than they are happy with. We want to feed our children but we can't force them to eat. You eating the same food at the same time can really help if you are not already doing this. Even sharing food from one bowl one piece each so he knows the food is good.
Hope this helps some.