If we had artillery, we could have combined arms. If we had airplanes.
The US has vast numbers of airplanes, by anyone’s measure.
The USAF is the primary battlefield weapon in the US system.
It is meant to deprive the enemy of its firepower, supplies, air support, and air defenses.
Artillery is supposed to help break open defenses for the mass of maneuver to exploit, not to bombard them for months. The US does not fight the way both sides are obliged to do in Ukraine. And the US has 4000+ artillery pieces, tube and rocket, including Active, NG, and reserve stocks.