(edited)
I'll take a stab at this with a few caveats. In general, ID'ing these birds from photos has some pitfalls. Along with the photos you would need to also post location of each photo as this will help rule out some species or confirm others. Additionally, habitat and "habits" noticed will also help.
The only completely accurate response would be KC's - these are all Darwin's Finches. The collective name for the 13 finch species on the Galapagos and 1 more from the Cocos Island.
Then by review of the beak size and shape and eliminations based on location we could get a good probability of the identification at the species level.
The two completely black plumaged birds are males and this coloring will further eliminate some species (such as the tree finches, warbler finches, and woodpecker finch).
Another issue is that of beak size variability. For example a Medium Ground Finch bill can vary to a size overlap with a Small Ground Finch on one end of the range to that of a Large Ground Finch on the other end of the range.
For a good table showing which finches are on which islands see this link "
http://people.rit.edu/rhrsbi/GalapagosPages/DarwinFinch2.html
At this point I will also confirm I am NOT an expert.
Good luck,
First group, first bird = small ground finch (based on apparent bill size).
First group, last bird = large ground finch (again on apparent bill size, with note per above that this could also be a Medium Ground Finch with a large bill. Habit could help with the identification here as Medium Ground Finches typically feed in flocks while Large ground Finches are generally solitary.).
Second group, first bird = a Warbler Finch (either Green or Gray, depending on island)
Second group, second bird = Medium Ground Finch
Second group, fourth bird = Small Ground Finch
Second group, fifth bird = Medium Ground Finch
