If you want to know why the ratings are centred around 1500 it is simply because this is the value in the original glicko2 paper [1]. It doesn't seem unreasonable for them to implement the algorithm as the designer specified.
With rating systems, the absolute scale doesn't matter, all that matters is the predictive power of the system. Every time I have benchmarked, glicko does a better job in predicting win/loss/draw probabilities than ELO ratings used by FIDE.
If you want to know your rating relative to other players on the site, you can check the distributions here [2]. If you want to compare them to FIDE ELO, or chess.com, you can use this site although I am not sure about exactly what methodology they use [3].
I wouldn't agree that lichess ratings are inflated or unrealistic relative to FIDE Elo, or any other rating system any more than kilometers are unrealistic and inflated relative to miles. They are simply different measurement systems.
[1] http://glicko.net/glicko/glicko2.pdf
[2] https://lichess.org/stat/rating/distribution/rapid
[3] https://chessgoals.com/rating-comparison/