When there are new skills and particular interests I always think it's worth following their lead rather than trying to distract with other activities. Your LO obviously wants to test out his strength and climbing skills and has temporarily lost interest in books but if you give him lots of physical exercise he might be happier to sit and look at a book when his body has had a good work out.
I would decide now which things you are going to allow him to climb and which you are not. Here for instance climbing (or even touching) the TV table was not allowed, ditto the book shelf...think ahead too, some things might seem ok for now but do you still want him climbing those things in 6 months or a year when he's bigger, stronger, fable to climb higher? I don't think it's too soon to start setting boundaries around the house.
Indoors activities such as
- climbing up and down the sofa or a foot stool
- creating a cushion mountain (low for a small LO) with sofa seating, bed pillows, duvets/bedspreads, bolsters etc to clamber across/up
- walking/clambering across uneven surfaces, similar to the cushion mountain but lower, some cushions with a bedspread or throw over the whole thing to make walking more tricky and challenging
- obstacle course (perhaps more for an older one) made of dining chairs, kid chair, table, foot stool, cushions
- obstacles, literally just putting things in his way on his regular routes through the house, I built a low brick wall (mega blocks or duplo) for DS to negotiate, whilst it's not climbing it is still a challenge
- large boxes/baskets, climbing in an out of laundry basket or a large cardboard box
Outside activities are often easier as you don't have to set so much up. Walking over uneven surfaces, cobble stone walks, up and down grassy hills at the park, or sand dunes if you are near a beach, play park equipment (mine was up the 6ft slide at 18 months with me following behind, breathing very deeply and gritting my teeth). Soft play centres are great for beginner climbers too.
hth