Honey, your baby is still practising chewing and swallowing skills. He is also developing his tongue and muscles' strength to bite, chew and move the food in and out from his mouth.
Also, he is developing his senses: the taste, the smell and the color.of the food...all of that are a lot of info for little baby to process. He looks like playing with his food, but naturally, that is the way baby learns. Hence the messy bib and spilled food.
If it is any comfort to you, my baby is 8 months, the mealtime is messy too.
Ps: for babies under 1 y/o, the main food is still milk. So weaning process is not about making them feel full, but developing the skills as I mentioned earlier.