Cindy, “newly made” meaning in the 1960’s or 70’s. The reasons for my appraisal, to wit:
1. It is made of pine. Most old boxes and chests were made of popular, basswood, etc. because they are much stronger wood and less subject to cracking, splitting and will absorb a much evener finish. To obtain an “even” finish when staining pine, one must first apply a 50/50 coat of shellac and wood alcohol to “seal the grain”, otherwise the knots and the grain will absorb more of the stain and will always be quite darker. #1 boards (knot free) are expensive now days, but 50 plus years ago, not so, they were still cutting monster trees for lumber. I still have a couple popular boards I saved from an old, old cabinet that measure roughly 4” by 24” and nary a knot in either one. (Now I’m rambling)
2. Too many knots (remnants of a limb) in the wood. In the old days a cabinetmaker would not use a board with a knot in it because they are subject to “popping out” or forming cracks and of course the “staining problem”.
3. Note the left and right edges of the back board in your 4th or last picture posted. Said edges are/were splintered off when the cross-cuts were made, a sign of a power saw being used and with the wrong type of saw blade.
4. Most wood will naturally darken with age and thus the older it is, the darker it will be.
Nuff said.