Reincarnation is not a teaching of the Buddha. In Buddhism the teaching is of rebirth, not of reincarnation. The reincarnation idea is to believe in a soul or a being, separate from the body. At the death of the physical body, this soul is said to move into another state and then enter a womb to be born again. Rebirth is different and can be explained in this way.
Forms come and go.
Buddhists are people and people do believe things, but Buddhism is concerned with truth, not with belief, and the teaching is to see things as they are. If we believe anything which has not been experienced, we should know what we are doing. When we do not understand something, then to maintain an open mind is the healthiest and wisest practice. It is the idea of a self living life through time, which produces the idea of birth and death. We have been conditioned into believing that we have come into existence and in due course will cease to exist.