Make your own fellowship.
There are seven classes in Lord of the Rings Online, and all of them are a completely different experience to play. There are no cookie cutter classes in this game, but there are also no really strongly defined roles. Depending on the class that you choose, you should have access to a relatively wide variety of abilities.
There are no dedicated healing and buffing classes - every one brings something to the table. The existence of fellowship maneuvers also makes it so that just about any fellowship can play together well, even in the most challenging instances. This makes it so that it is far easier to get a fellowship together in LotRO than in other games - you don't have to stress so much about whether you'll be able to get a group when you select your class.
In keeping with the established fiction of Lord of the Rings, none of the classes use real magic, and upon losing all of your morale, your character only "retreats" rather than dies. In game mechanics terms, many of the abilities act like spells, and when you run out of morale - which is essentially health - you die. The minstrel, lore master, captain and guardian all have healing abilities of some kind or another, and can keep a party on their feet if they choose to focus on it. The champion and hunter are almost exclusively focused on doing damage, and burglars have a number of tricks up their sleeve to trip up their enemies.
Any class can solo effectively up to the maximum level, especially if you stick to the quest lines offered to you. Damage dealing classes will be able to do it faster, but not so much that it becomes a chore to level up. You won't find any situations where people will say that they can't do an instance unless they have a certain class. It certainly helps to have a dedicated healer and tank, but guardians, captains and champions can all fill the latter role quite well.
Burglar: A class with an endless array of tricks at their disposal, this class has access to powerful stealth abilities.
Captain: Captains are strong leaders capable of buffing their allies and striking fear in the hearts of their enemies with battle cries. They travel with an AI-controlled herald that adds to their damage capability and utility.
Champion: A deadly warrior specializing in two handed weapons and dual wielding. They wear heavy armor.
Guardian: Guardians are protectors capable of shielding their allies and unleashing powerful retaliatory attacks.
Hunter: These travelers use bows to destroy their enemies from afar along with traps to keep them at bay.
Lore-Master: These wise sages use their knowledge of the ancient past to confound their enemies and invigorate their allies. They travel with various animal companions.
Minstrel: Bards that use music and lore to restore the spirit of their fellowship.