Why can’t I play the melody when I play according to the guitar tab?

I have just started learning guitar now. I can play some chords and can also read guitar tabs. You might as well listen to any song and you will find that the background music of the song (that is, the accompaniment music) ) cannot be the melody sung by the singer. If the accompaniment of a song is the same as the melody sung by the singer, it is not called accompaniment. If you guessed correctly, you should be playing the accompaniment score. What is the function of accompaniment? To sum up, there are the following: first, it reminds you of the speed and rhythm of the song; second, it reminds you which key the song is in (that is, what the tonic is); and finally, it reminds you of the melody of the song you sing. Cooperate with each other, remember, "cooperate" rather than "identify". For example, our school once held a New Year's Day party, and a girl sang "I Really Miss You" for everyone. I think you should know that there is an erhu solo before this song. At that time, a teacher used the erhu to accompany her. The intro was the intro at the beginning, which sounded pretty good. But after the girl started singing the song, he followed the melody of the song completely, that is to say, he sang along. The girl played the erhu to the end of the piece. To be honest, it felt terrible. It wasn't that he didn't play well, but that it wasn't accompaniment at all. Real accompaniment is not a repetition of the melody (which allows for small repetitions of the melody), but the use of chords to match the melody of the song being sung. After talking about the accompaniment, I want to talk about what you call this song. If you get the score (melody score) of Chrysanthemum Taiwan, you can try to play it, and you will find that it is very "dry" - that is, there is only melody without accompaniment. Instrumental compositions, especially those for harmonious instruments, are not just composed of melody sounds, but also include accompaniment sounds, and sometimes there is a second or even third part of the melody. If you really want to "play" the song, rather than sing it, you must find the sheet music with the accompaniment. But judging from your question, your knowledge or understanding of guitar is not deep enough, so if you really find this piece of music, it may be very difficult to play it. I personally think that if you want to play a solo piece adapted from a song, you must have at least some basic skills, after all, it contains chords and melody.