Is it normal to feel untalented?

You compose? That's amazing. That takes talent. Yes, once you get the hang of something, it seems meaningless to you, but if someone just starting to learn saw you I'm sure they'd be amazed.
I played keyboard for a little while, and although I love it, I don't have the natural talent for it. You need to have a strong sense of where each finger is and where the keys are in relation to them. I was never able to learn by reading notes, I had to copy someone else doing it. Reading music is like (to me) another language, so you compose, read, write and play music.
You can't be good at everything. So what you can't design, or animate? If everyone could, it wouldn't be so amazing. Just like not everyone can play an instrument and compose music. You might think it's easy, but that only shows that your amazing at it.

You are talented! It's just that when we find something easy, we don't think it's a talent, but it is. I read an article about this recently. I know what you mean and I think it's a common thing to feel. Maybe you're comparing yourself to others too much as well. Remember there are plenty of people who wish they could play keyboard who would be envious of your TALENT! : )

You are so far off base that I shudder to understand your thought patterns.
In the 60's I was a roady for a few of the great San Francisco rock bands and even with the help of some of the most talented musicians alive, I could not be taught "talent". I was not then nor am I now ever going to play any instrument, even for my own pleasure. Sure, I could do the mechanical thing of moving fingers, but I have no rhythm, timing or understanding of what music is really about, technically.
Consider yourself lucky and enjoy the gift you have been given.
By the way, many of my professional musician friends have become bored with their primary instruments, too and moved on to more difficult ones like the pedal steel, sitar, etc. They travel the world listening to and learning from the local musicians, who play so differently from we westerners.

I dabble in a little bit of everything, so I feel like I haven't fully mastered anything I've tried - or at least compared to other people, it's just never enough.

Do you know what I would give to know how to play a piano??? You certainly have no idea how much people love music.

You have talent. Because you consider keyboarding and composing to be easy, and many will find it impossible! But I can totally understand the reason you feel this way. If you feel that you've mastered your hobby why don't you take your talents to the next level? Or discover something new to master? You say that you couldn't animate a cartoon, carve a statue or program a computer.. How do you know? Have you ever tried? If these are things you would like to achieve and then actually value them as achievements, then pursue it! I believe in you, just go for it! :)

Well I know computer programming but I don't think I'm talented.

lol animation is easy too, if you're going to simplify things like you did with keyboard playing, it's just drawing/modeling successive frames. I can animate but cannot play music for shiiit it's really not as easy as you say, it takes coordination, intonation, rhythm. any person can perfect an instrument?? I never could... any person can perfect drawing, animation, and all the other things you've mention, they are skills rather than talents. I suppose music is the same, but those with more ''talent'' will get the hang of it faster...so a lot of people give up on drawing or music (like i did) especially when everyone around them excels at it with little to no practice.

People who are talented something do not have to try very hard at it. Since they naturally are very gifted or inclined to do that subject. You are just angry you are not getting a challenge out of it. Try doing something you are not very good at and see how that serves for you.