Origin

There are five origins in the game each of which describes a different way that your hero gained their powers. Information about the significance of origin selection is very hard to find so here's a nice consolidated explanation:

Later in the game, you will get Enhancements that are Dual Origin and Single Origin. If you want to get useful enhancements from the enemies you're fighting, you'll want to take missions from certain contacts and fight certain kinds of enemies.

For example, if you are of magic origin, fighting CoT will give you magic enhancements, but not fighting Nemesis. You'll find that you fill up on enhancements very quickly when you never get any you can use during a mission. Therefore, you'll often want to follow contacts and story lines that match with your origin.
Your origin determines your initial contact who will direct you to missions that are aligned with that origin. While later on, you can make choices that change the way you play the game, origin does determine, to a small degree, the story arc you take through the game and the first enemies you'll fight. See HERE for the full listing of early enemies as well as their resistances and weaknesses.
Recently, the Devs added a temporary power based on your origin that you keep until level 10. They are designed to help you during the early part of the game and could accent your character design (powers described below).

The origins are:

Natural

A natural hero is either highly trained or is a member of an elite group or alien race where all of their kind have this type of power.

Temp power - Throwing Knife. Does a small amount of damage plus DoT.

Early enemy - Council. Escpecially at low levels, council are a simple type of enemy to fight. They are good for beginners to face off against, but might not be as fun to fight as some of the other groups.

Science

A science experiment or accident caused the manifestation of powers. If you get creative, this one can work well. For example, I had one hero who was a robot, but rather than Technology, I said he was Science because he was actually a human who's persona was transferred to the robot during a laboratory "accident" which was actually a failed assasination attempt.

Temp power - Tranquilizer Dart. Minor damage plus sleep.

Early enemy - Vhazolik. This enemy type can be very tough for Squishies so you might want to choose something else to avoid missions with them.

Magic

The magic of this hero can come from within, from training, or fromm a powerful artifact, but either way they have tapped into the forces of the universe and learned to control it. This is one of my favorite types only because I like writing the back-stories of magic heroes.

Note that in later levels, the enemies that drop SO enhancements are CoT and Carnies. Carnies are very tough on squishies and CoT are the #1 hated enemy in the game because of status effects like holds, sleeps, slows, reduced accuracy and such.

Since my first magic character was a Regen scrapper, I didn't have any problem with these groups. This is because scrappers are tough enough for carnies and the Regen powerset has a power that makes you all but immune to all knockbacks and status effects.

Temp power - Apprentice Charm. Minor damage and lowers RES.

Early enemy - Hellions. Basically just a street gang. The toughest thing you'll fight at low levels is a fire user or two, but they're basically just a knives and guns type of crowd. The biggest advantage to fighting them early is they're EVERYWHERE in Galaxy City and Atlas Park so Hunting missions will be easy since they're not hard to find.

Mutation

This hero was born with a mutation that makes them different from the others around them. For reference, all X-Men are mutant heroes.

Temp power - Mutagen. Does minor damage, reduces damage potential of the enemy and has a slight chance to choke the enemy for a few seconds.

Early enemy - Skulls. Another gang that won't give you much trouble. The toughest early enemies are "Bone Daddies" who have basic darkness attacks.

Technology

Again, not super, but has super gadgets. They could be the brilliant person who created the technology or they could have recieved the tech from somewhere else.

Temp power - Taser Dart. Minor damage and chance to hold the enemy temporarily.

Early enemy - Clockwork. They are fun to fight because they're the most interesting of the early enemies, but they can be harder to find for Hunting missions. They do have some status effects so they'll be harder than Council, Hellions, or Skulls.