It has been pointed out that there is an obvious sense in which 'I' exist. For instance, one can say 'to prove I exist, here is my hand' and then hold up one's hand. While this is clearly the case, one must then ask what 'I' means in this context. It refers to the location from which the voice comes that says these words.
However when we use the word 'I' in other contexts we imply some kind of being that has thoughts, desires, relationships, possessions and some kind of continuity. Nevertheless the thoughts change from moment to moment, desires are fluid and influenced by mood and the whim of the moment, we can lose or gain possessions. We really feel the fluid nature of 'I' when a major relationship is ended or a new one begun.
The meaning of 'I' implying a location of the speaker at that moment in time (as in 'Here I am!") does not necessarily imply the existence of a continuous being, whose utterance of 'I' in the next moment is not necessarily the same 'I'.
What endures is only presence.