I of course tasted beer before I bottled it all up and it tasted a little watery, is that common? It's a muttons nut brown ale
Uncarbed beer doesn't taste like the finished product. Don't worry.
Yes, without carbonation the mouthfeel certainly is less vibrant.
When beer is carbonated it adds carbonic acid taste and bubbles of course so a beer that had been chilled and carbonated will taste completely different than pre bottle. Just give it time
Never judge a beer until it has gone through the entire process.