Galen was like this around 5 months and I resisted for a while longer because of the chew ability and feeding himself. TBH I didn't want to go the puree route and so eeked out another couple of weeks to be able to go with BLW.
I started weaning Galen when we was 5 1/2 months and have more or less done BLW but its been fiddly because as has been said you can only really give fruit and veg before 6 months. He had 2 servings of baby rice mixed with EBM to start and since then has had cooked veggie sticks and fruit. Its a lot of effort as until his chewing gets better he can't have small fruits like blueberries and I am avoiding pureed foods other than apple. He feeds himself that off the spoon and I've started mixing in natural yogurt also with it. And yogurt on its own. So it means roasting small amounts of food that is going to be soft enough for him to be able to bite and chew.
Also you might need to be more careful about how quickly you introduce each new food so as to make sure it agrees with him. The first week I gave Galen the same thing at least 3 times before introducing a new food.
So far her has eaten
Carrot sticks
Broccoli florets (both steamed)
Butternut squash
Parsnip
Sweet potato (all three roasted)
Celeriac
Pear (sliced into sticks)
Banana
Stewed apple (left lumpy)
Kiwi (slices of)
Natural yogurt
He isn't eating big amounts, often its more about playing with it, getting a taste and so on. We are a few days off 6 months now and I am so looking forward to being able to give him other foods now. Its been a long two and a half weeks so far.
I'd consider waiting a couple more weeks at least for the chewing factor and also the feeding himself aspect. Even though he seems keen he isn't lacking anything nutrient wise and it will mean he is closer to the age where those things will start naturally.