Hello,
you have added 3000 nodes, without ever adding any attributes, some of which seem to be buildings (but which are sometimes already present in osm).
To make a building, select ‘line’ in josm and then add the building attribute.
When you send it, it's essential to look at the validator window, as it should have warned you of the problem.
I advise you to start smaller: make a few houses and, if you wish, let me know here so that I can give you my opinion.
Happy mapping !