People can exist without being of any spiritual or ethical importance - that Jesus of Nazareth is admitted to be a really historical person, does not by itself tell us anything about Him. (Names by themselves are no guide at all as to whether the being named is historical or fictional.)
Rabbi Akiba (for instance) is very definitely an historical person - that does not tell us whether he is important within Judaism, nor (if so) in what way (In fact, he is rather important - he is one of the Jewish martyrs of the second Jewish war against the Romans.) To most Christians, he is probably not even a name.
As with him, so with Jesus - “Jesus existed” is an historical judgement, which could be made about tens of millions of other people: it is useless as a guide to answering the question “In what way is this man significant” - because historical facts are not judgements of value: to say that say somebody is significant in this way or that, is a judgement of value. And one cannot go from the one, to the other - because the two kinds of judgement, judge things that are completely unrelated.