Rainwater typically has a TDS of 20 mg/L or less. Fresh water from lakes, rivers, and groundwater is more variable, with TDS ranging from 20 mg/L to approximately 1,000 mg/L. Brackish water is, by definition, water with TDS exceeding 1,000 mg/L and ranging as high as that of seawater, at approximately 35,000 mg/L.
Is rain, too, not salty?
Compared to a river, yes. Compared to the ocean, no.
https://watereuse.org/salinity-management/ls/ls_3d.html
No. The salt gets left behind when water evaporates.