Hey, welcome!
This clearly is not an O'Day DaySailer. It does like a Javelin. If the sails have the J with Javelin insignia, that may confirm it, also, you can measure length and beam (width of the boat) and compare to the specs on
https://sailboatdata.com/sailboat/javelin-14-foxIn many ways the Javelin is like a smaller sister to the DaySailer. Much of the discussions here are generally applicable to boats of this type (centerboard, sloop rig, that is main plus jib, or what you call the "front sail"). Some people here may have seen or sailed on a Javelin, but most of us are unlikely to give you the same model-specific advice as another Javelin owner.
I would put the main in a bathtub (if you can get your hands on a bottle of sail cleaner, like sail wash, the better), soak and scrub gently. If the threads look like they are in good shape and the fabric isn't "rotten" - that is, the polyester fabric isn't too badly UV damaged, or attacked by mold, then you might be able to use it for your first practice sail. You are right, new sails are in your future, but you'd be surprised how pricey they are (compared to a free boat

) and you'd want to be sure that sailing is definitely in your future. (That is, you'll get good use out of your investment).
While you are cleaning everything and checking that you have all the parts, you might want to look at the thread on "
Basic Concepts and Techniques" here.
Finally, if it is a Javelin, DR Marine may have type-specific replacement parts.
Good luck! Let us know if you managed to rig and / or launch her.