Babies really need to try a food approximately 15x to determine if they really don't like the food. Often in the beginning they might be questioning the taste, texture, or they might not care for it but I would keep trying it every few days. I even find my 4 year old DD loves oatmeal one day and says she is allergic the next!
If you are making your own it's handy to freeze cubes of food, that way you have it on hand to keep trying every so often and you are not wasting too much of it when lo refuses it.
All los are different in terms of texture- purees/finger foods/texture, but I would say that by 8 months all los should be exposed to more solid food (non puree) to get used to the textures otherwise after that it might be harder as they may refuse texture. Don't worry if your lo has a preference for only a few select foods, just keep trying new ones all the time and don't get stressed. At this age it needs to be a fun and exciting experience for los! You can go ahead and try more texture or lumps, you'll know if your lo is ready yet.
Ripe banana is rather soft, so if it's offered in small pieces for baby to mush into his/her hands and eat the chances of choking are small. I would consider it a good early texture food. True choking foods are solid foods that are round and can block the passage (ie. solid grapes). Though with that said a friend of mine had her dd really choke up on a huge piece of banana that she shoved into her mouth. Thus the need to always be with lo when they have food at hand!