Trending @Accenture; Whats the role of Team Lead

I really have a doubt reg role of TL. In my project there is a TL who joined in last dec and from that time he gets help from me for everything..he ask me what to do in each situation... morning when he comes he just assign tasks and whatever task AM ask ..he ask us to do..he will take some simple lower environment tasks.. not any production tasks and if there is any bug he will assign to me or others....my AM is also fine..in our group she asks him to assign the task to others..I can see him joining 1 call daily..other than that he doesn't have any work as far as we know..one time our manager has told me she knows that he is not taking much tasks ..i initiated one automation but I couldn't present..but my am knows that ...but still they didn't give me promotion...it's been 4 years as sse ...and l had a clash with my AM...so now everything is on my head and I don't know what to do..i want to ask them why tl is here...but I can't... really I am doubtful about the role of TL...is it this simple? I thought when we go higher level..our responsibility increases and we need to take complex tasks which sse se ase can't do...am i wrong?