I think you will be fine with the food onboad. You didn't say how old your baby is, but for babies older than 6 months (the age when the American Academy of Pediatrics recommends starting solid foods) jarred baby food is essentially "convenience" foods anyway.
I never used jarred baby food for my babies except on rare occasions when we were traveling and I wasn' t sure whether there would be anything proper for baby to have. As long as I had access to some bananas to mash with a fork, or steamed carrots to mash, or oatmeal made without milk, etc, we were fine. The suggestion about steamed vegetables is a great one. They also will have no problem fixing a plain chicken breast which can then be cut in very small pieces or partially pureed in the kitchen. If your baby is anywhere close to one year, the food selections will even be easier.
There is an abundance of fresh fruit onboard and different whole grain breads. Just ask your waiter for anything else your baby might need - you don' t necessarily have to stick to foods on that day's menu . They will do all they can to help you. As an added bonus, the fresh food will taste much better than the jarred stuff!
Ruth