If you take into account the society, the culture and the way of thinking of one certain period, then you can find any kind of historical character relevant for the 21th century. E.g. Jean Jacques Rousseau was a mysoginist but still he is one of the writers who inspires us the most due to his ideas and his "freedom" of spirit, seen from the lenses of the XVIII french society. If you take a historical character and you analyse it from the point of view of someone from this century, then you'll need to do a very hard job to find at least one character to be admired

Most of the time I feel like we would be desperately lost without them. Who alive now compares to Plato, Cincinnatus, or Sandor Marai. The era does not matter; the great figures of humanity will always be with each generation serving as a beacon for when we lose our way, as we inevitably do.

I think it's bad idea to take historical or every other person as a role model. Every human being is unique and has own life and way. Share their ideas but don't try to copy their lives!

I don't know in this time if their presence would make a huge impact like before. Is interesting to think how people would react to them in 2019, no?

Yes,they can. There are so many historical figures that whatever your taste or ideology is you can always find a valid model.