Actually, Kyiv and all of Ukraine was the original goal, except that the Russian attempt at a coup de main was a spectacular failure.
There were a couple of places where the coup de main strategy worked. One was in breaking out of Crimea, and the other was in crossing the Dneiper and taking Kherson. The combination of fast moving armored columns and “silver bullets”, the bribing of Ukrainian government and military officials, worked there, if nowhere else.
It succeeded in giving Russia the Kherson bridgehead, and in turning the Ukrainian southern flank, exposing Mariupol to encirclement.
Unfortunately for the Russians they didn’t allocate sufficient forces to the southern operation to exploit their breakthroughs as much as they could have, in a second stage advance. A third of the force allocated to Kiev could, likely, have taken Mykolaiev, on the road to Odessa, or taken the Dneiper line from the rear, isolating Eastern Ukraine.