Connect to pre-wired Cat5e (no clear demarc point)
You won’t use the cable going outside.  You would use that if you had phone company DSL instead of  cable.

To make your other Ethernet outlets hot you need to add keystone jacks at those location as well as the location of the Comcast modem.  (Use the T568B wiring standard throughout— you could use T568A and it will work—568B is more commonly used—whichever you pick, stick with it for all jacks, or it won’t work)

You also need to purchase a “fast internet switch” (yes I mean search amazon or google for exactly those words).  It must have enough ports for the number of wires in the basement (minus the one that goes outside.  (“Unmanaged” is the type, but don’t include it in the search because not all have that label, but many do—- don’t however purchase anything with the term “managed” for this application.)

Using an Ethernet cable connect the keystone jack by the Comcast modem to a Lan port on the Comcast modem (we are sending Ethernet to the basement with this connection). 

Now connect all the cables in the basement to the Fast Ethernet switch.   The wiring cabinet may have provisions for jacks, but if it doesnt the simply way is to buy cat5e surface keystones that hold 2 or 3 jacks and just wire them inside the basement panel, then use short Ethernet cable to jumper from those to the jacks on the switch.