From this age of aviation almost ALL are replicas. There are originals still out there...but most often you will have to visit museums to find them and they are almost always NEVER flown. These were all wood and fabric aircraft, and deteriorated much faster than WWII or later aircraft.
Yes SLN those are all what you'd call home built. The Foker D VII, Dr I and D VIII are all full scale and flew in from Colorado, they had to stop every hour or so to refuel.
The rest were 3/4 to 7/8th scale I think.
I'll be posting pics from inside the museum soon and a couple of the WWI planes on display are even replicas. Although those are built exactly the same as the originals.