For 6 months old, they have just started seeing colors for 1-2 months, so they will be drawn to Red or Colorful items. Babies will often get curious with a lot of things, movements and sounds as their sensory needs heightens.
From 6 months onwards, they will start to strengthen their grip control and legs. They will like to chew as teething starts and they get captivated by moving objects while sitting still in prams.
They will also start to develop their hand & eye co-ordination and motor skills. Generally, coming to the end of their first year, babies learn to focus their vision, reach out, explore and learn about the things that are around them.