If you are a beginner swimmer i would put most of the effort there to begin with. Swimming is the most difficult to learn and to master. It doesn’t come naturally and you really need to practice to correct any bad habit you might have. If you are consistent, running and biking you will get better as time goes on if you put time and effort.
In the other hand, swimming can get worse if you dont take care of it early.
Find a master group of an instructor to make sure you perfect your swim.
Take it from me. Im a terrible swimmer! like VERY VERY bad. It has cost me AG podium awards. (i am usually the last one out of the water…ALL AGES).