You have asked a very broad question that would have benefited from being a lot more specific. I have included links below to the enotes study guide section on this excellent play that should help you learn more about the full range of themes and meanings in the play, however, in my response, I will focus on the presentation of men and monsters.
One aspect of the play that is well worth investigating is the presentation of Caliban. He is shown to be reviled by Miranda nad Prospero. Miranda for example says that when they first arrived and she taught him how to speak, he resembled a "thing most brutish" in the beast-like noises that he made. In addition, Prospero in particular is very violent in his speech towards Caliban, calling him a "born devil." Although Miranda and Prospero believe that their influence on Caliban's life in terms of the education that they have given him has "improved" him, at the same time, their view of him as being a sub-human savage remains unchanged. From their point of view, the beast-like part of Caliban is infinitely more influential than the human part, in spite of all their work. Although it is claimed that Caliban tried to rape Miranda, the way he is kept in slavish servitude stresses the inherent belief in their own superiority that Miranda and Prospero possess.
Of course, these two principal characters are not the only ones to interact with Caliban, and Trinculo in particular when he first sees Caliban in Act II scene 2, points towards the ambiguous view that the play presents of Caliban by deliberately blurring the distinction between how we define men and how we define monsters. Note what he saysin describing the attitude of those in England:
There would this monster make a man. Any strange beast there makes a man. When they will not give a doit to relieve a lame beggar, they will lay out ten to see a dead Indian.
Note how in this quote what is truly monstrous is not the appearance of the "strange beast," but the way in which "men" will walk past a "lame beggar" without giving even the smallest of coins, but will glady pay high prices to see some kind of freak. Thus categories such as human and inhuman are profoundly questioned through the character of Caliban and how he is treated, suggesting that a lot of us are actually a lot more "monstrous" and "inhuman" than we would first suspect, given the way that we treat others less fortunate than ourselves.