As far as lyrics go I was lucky that the words I wrote were original, but music and beats were a different story. When I was 15 or so and still learning about sound editing I'd download random backing tracks and try to loop instrumentals to try and make a melody. I can write lyrics but making melodies is super hard for me and I don't understand why. I've had perfect pitch since before I could talk, all I did was hum and if the note I was humming matched the note of the sound I was happy. Eventually I just kept at it and then when I learned how to talk I started singing shortly afterwards. IF someone were to write a song and give one to me I could sing it no problem, but trying to make my own melodies, well, let's just say it doesn't really go all that well.