It's fine. if it's not only source available but also open source, you are giving your users the four free software freedoms. That's already huge. They can stu

It's fine. if it's not only source available but also open source, you are giving your users the four free software freedoms. That's already huge. They can study the thing. If someone wants something you don't provide, they have the right to make their own derivative. Possibly with open contributions. You can take from these forks if they are public and open source too (but you control what you take and how). If closed to contributions is the way you prefer writing your software, go for it! And you can always change your mind if needed. Taking contributions can be very fulfilling, satisfying, nice and everything, but it can also be tiring since it can require to be pedagogical, polite, possibly make compromises, argue, etc. Your call and thanks for releasing your software in any case :-)