There is nothing wrong with imitating your favourite singers. In fact, I highly recommend it!
Imitating vocalists such as Whitney Houston, Florence Welch, Katy Perry or Rihanna will not result in loss of identity for you as a vocalist. If done with awareness and knowledge this will only enhance your ability as a singer.
The talent for mimicry is not unlike any other singing talent. It’s a bit like being an actor. Just because Meryl Streep may fully inhabit the character she is playing in a film does not mean that she BECOMES that character and loses her own identity! The same idea applies for you as a singer.
I fully explore this in my lessons. ie copying other singers as a means to develop your own talent.
Its all about learning to use your voice and if you imitate other singers then that is one step towards that.