Mixing the lighting with the receptacles are commonly done for two reasons. The lights won't use anywhere near 15 amps leaving a branch circuit rather minimum loaded in amps being a bit of a waste.
If you mix part of the lights on one circuit and part of the lights on a second branch circuit the entire basement won't likely go dark at once.
If you are wiring the branch circuit wiring then you are no safer. You only have three wires to connect in the panel to a new 15 amp single pole breaker if 14/2wGrnd cable or 20 amp single pole breaker if 12/2wGrnd cable.
The white and bare connect to the neutral bar and grounding bar and the black wire connects to the lug of your new single pole breaker.
More fires happen in the branch circuit wiring than in the panel. If you are doing the branch circuit wiring you might as well do the panel wiring. Just turn off the main breaker in your panel before you connect in that panel and be sure to use a breaker listed for use in your certain brand and model of your panel. Your choice, don't see why not do it all.
Good Luck
Wg
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