The average player in school tournaments has a rating of around 600. A strong player who doesn't participate in tournaments, or a beginning player who has gained some basic experience, could have a score of 800 to 1000. Do you want to improve your chess skills? I imagine that the average ELO has dropped a lot recently due to the huge number of new Queen's Gambit players and other examples of chess that have suddenly become popular. However, chess rankings are highly correlative between different systems, so improving chess skills online should be transferred to the game above the board.
Modern chess classification systems have existed since the mid-20th century and have been implemented both by online chess sites and by in-person chess federations (OTB). In fact, we would like player A to win more than 16 points and player B to lose less than 16 points depending on the reliability of their ratings. A Comprehensive Guide to Chess Ratings, by Professor Mark Glickman, contains more information on the history of chess rankings. There is no average chess rating, but a solid chess player at the club level could have a rating between 1500 and 1700.
In general, as players play more games or have higher scores, k-factors decrease, allowing these more established players to have ratings that are also more stable. In the 1990s, I was helping my local club calculate club rankings using a table similar to this one for established players. In 1948, the West German Chess Federation used the Ingo system, possibly the first documented chess classification system. On average, chess sites refer to the rating of all players divided by the total number of players on their website.