Mine is 5 months, here are some things he likes:
Pulling sensory scarves out of a cardboard box with holes in it
Water play - pouring water out of little plastic cups etc
Building stacks of cups, putting smaller cups inside bigger cups, knocking cups over etc
Length of silk ribbon tied to a stick, twirled around over his head
Bouncing games on my knee
That toy where you push shapes through the holes in the lid of a box
Baby massage
Rolling a ball to me, back and forth
Sensory bottles (water bottles with water and glitter etc, or no water but rice / pasta, lids superglued on)
Sensory pouch (laminating pouch filled with shower gel, sequins and buttons then ironed at the seams and strengthened with duck tape
Peeling lengths of tape off of his high chair tray
Singing and clapping to nursery rhymes
There are two great Instagram accounts with loads of ideas for activities with babies - one is called something like ‘an activity a day’ and the other one is ‘everyday we play’. They’ve given me loads of great ideas.