No cold air return in home
Even if you just cut a hole in the first floor floor and mount a grill there to provide the furnace return, that should be ducted directly to the furnace and not left open to the basement air.
In some houses, the space in the wall between two studs is a return air duct with appropriate grills in the wall as needed, and stud plates/stud caps cut away to let air come down from the second, third, etc. floors.
A problem that can arise with just recirculating basement air is radon gas, which finds it way into many basements in many regions of the country.
If a particular room or bedroom does not have its own return air duct, then the door has to be kept open to the hall in order to get good heating.
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.