心中是一片火海 - My heart is an ocean of fire
无法容下世间之爱 - It cannot contain (accept) any love in the world
但愿无声 自有人在 - Just wish (when I am) voiceless, there is always someone there (to accompany me or speak for me)
但愿无能 自有人在 - Just wish (when I am) powerless, there is always someone there (to accompany me or to help me)
The problem with the phrase '自有人在' (there is naturally/ always someone there) is it doesn't state what that person is supposed to do. I have to presume that someone is there to accompany me or actually be there to help me
Typical usage of '自有':
你不爱我自有人爱我 (you don’t love me, naturally there is someone else who would love me) = Even if you didn’t love me, there is always someone who would love me
Common expression: 山人自有妙計 = I naturally (always) have a good plan