In Jumanji: Welcome to the Jungle, after Alex Vreeke meets the four other players, he takes them back to a house in the jungle where he had been living for the past 20 years.
Alex explains that the house was built by Alan Parrish, the last person to play Jumanji. He knows this because of a note scratched into the house:
Alan Parrish was here
How did Alex Vreeke know that Alan Parrish was a previous Jumanji player?
In the original Jumanji, Alan Parrish was trapped in the jungle for 26 years from 1969 to 1995. In Welcome to the Jungle, Alex Vreeke was trapped a year later in 1996, so the two couldn't have met each other.
It makes sense for Alex to assume that Alan Parrish built the house, but the note doesn't say anything about the house being made by a previous player.