Ducks can attack humans if they feel threatened or if the duck thinks you're a threat to their baby ducks.
However duck attacks on humans are very rare.
Most ducks are very friendly and love being around humans and will not attack humans unless absolutely necessary.
I've been around ducks a lot and we had ducks growing up on the farm.
The ducks on the farm were really great friendly ducks and never have tried to harm anyone who got near them.
I had a few ducks that would love to sit near me and would want me to pet them.
Even one duck I had liked to sit on my lap out on the porch.
Not all ducks will do that but some do.