Somebody asked at my seder this year why Moshe is largely absent from the magid. I have heard that the reason is because we're supposed to focus on God, and also that Moshe was very humble and there might be a midrash about him asking not to be in it. But I can't source any of that. Are those the reasons? If not, what is? And either way, what's the source?
Bar Ilan University's parsha site had a discussion on this several years ago. There, someone wrote that the Samaritans in particular considered Moshe a demi-god and only accepted the first five books of the Torah as authentic.
As part of Chazal's post-Churban attempts to establish and maintain a set of core beliefs, Moshe is only incidentally mentioned in the haggadah (because we tend to cite complete verses). Other than that, the focus is on haShem.
There is also substantial scholarly literature on the polemics inherent in the haggadah. For example, where Rabban Gamliel indicates that we are to explain the three symbols of Pesach very specifically, it has been proposed that he was remonstrating against another community that had a very different view as to the meaning of the paschal lamb and the matza (and so too, perhaps, marror).