Roughed in electrical wire tucked in the ceiling by builder/electrician
I put in extra circuits quite often. They could have been for an option on the home that was not purchased with a speculation /track home (homes being built prior to purchased)  it is cheaper when you hire a roping crew (they just pull wire based on the generic blueprints) then the electrician  goes in and connects everything. If you don’t buy the upgrades they are not connected in the service panel.
So they may be spares for additional lighting and or receptacles.
Ask your builder to be sure but this will be the most likely answer.
Don’t cut them off if you decide to use them in the future having them can save hundreds dollars for each circuit.