The first boss is soloable
By solo-able I assume you mean incredibly easy.
The second time I want after the guy, I killed him pretty easily. My warrior was still (and still is) only level 11 but I'd added the crystal things to my weapon and my tunic. I was about 1/3 health when the beast died.
It was easily the hardest encounter yet in the game, but really compared to the number of attempts I've made on other bosses in other games, nailing it on the second attempt would still land it in the sort of easy column.
What has made this game so incredibly easy so far as been the lack of agro from hostile mobs. They really only agro if you start getting sloppy with the area effects. Is there proximity agro in more difficult areas?