Adults do need play, learning and fun.
However you could also expect them to have more sophisticated palates than children, and actually to stretch themselves to learn and play in ways that are appropriate for the brains and emotions adults have got.
Adults can do things that require focus, commmitment, fun and energy, and also require the person to have the autonomy and agency to engage fully. They can do things where the ADULT reward is greater because the ADULT investment is greater.
Dance classes
Cartoon drawing
Comedy improv groups
Music playing in groups together
Animal visiting - at zoos, in evenings after work, in farms, in places where you might want to walk a bit to get to them or see them in more challenging habitats. Go on a safari.
Understand animal conservation, respect animals, maybe watch a film about rabbit life. No need to touch the rabbit, they don't specially like that.
Theme parks - again, the bigger thrill rides or rides for adults.
Cultural events like carnivals, gigs, fairs, plays, shows, sports matches
Museums with more complex displays and shows and where the learning is more complex. Not an animatronic dinosaur made of rubber.
Art galleries where subtle emotions and ideas about the human condition can be considered.
Restaurants with a range of foods catering to adult palates.
Children's tastes are being formed. They need a mixture of safety and challenge to learn and play. Safety plus challenge is vital for their stage of development.
Now the thing is -
Challenge to children is safety for adults.
Fun gentle music of a simple nature
Characters dressed up in bright colours teaching you about stuff through songs, rhymes, simple stories
Decorations and styles with appropriate levels of story to teach you BASIC things about the world ("This is Farmer Squirrelnut's Barn where he milks the cows!" "This is Snow White's house!")
= Challenging, stretching, exciting content for a 4 year old child
= Infantile, overly cosy, brain mush content for an adult
This is why I would judge or feel a bit sorry for an adult going deliberately to child focused events regularly and as a preference over other activities. They have some kind of lack in their ability to soothe themselves and some gap in the development of their ability to learn and play. They are only OK with the safety, not the challenge. It is junk food for adult emotions but enriching content for child emotions.