Aragorn is a Cleric

Knight of the Road
OK, I know this isn't a novel observation...even if I had never surfed the web, I think I could guess accurately that gamers have noticed before how some of the abilities of J.R.R. Tolkien's Ranger/King and White Box Clerics overlap. From the turning of the undead wraiths on Weathertop to the healing of Frodo (enough to get him to Elrond's better care) the idea that Aragorn has some Cleric abilities jumps right off the pages of the LBBs.
In addition to the spell Cure Light Wounds, there are several other Cleric spells which seem compatible with the Aragorn character. Protection from Evil, Find Traps, Neutralize Poison, and perhaps Speak with Animals, Remove Curse, Cure Disease and Speak with Plants, all seem possible spells Aragorn might use. This has occurred to others as most iterations of the Ranger class have included the ability to cast at least some of the lower level Cleric spells. Often, the Ranger is given some mastery of Magic User spells as well, but these seem less Aragorn-like to me.
Aragorn's influence with the undead at Weathertop and later in the Paths of the Dead suggest some power over spirits which others do not share. Perhaps this is due to Dunedain or royal blood. It could be that all Rangers are Dunedain. The Dead Men of Dunharrow owe Aragorn and his family a debt, but that may not explain totally his influence with them. It could be his connection with life forces or a mystic thing. There are lots of ways to explain fictional abilities.
The Clerics class as written doesn't fit Aragorn with regard to weapon restrictions, but redefining those and adding some woodcraft we could come up with a Ranger sub-class of Clerics rather than of Fighting Men. The LBBs don't deal a lot with religion or deities, but the name Cleric suggests a religious connection. Aragorn is definitely not a priestly character and perhaps the sub-class would need to make this religious estrangement abundantly clear.  The source of Ranger divine magic abilities being their connection to royalty, or nature or elf-lore or something other than deity worship and prayer.
On another level, that of purpose and principle activity, Aragorn and the Rangers of the North and the historic Knights Templar and Hospitaller military monastic orders, who are arguably the model for White Box Clerics, were devoted to protecting travelers and defending the realm. They would patrol the land and watch and offer aid in the form of physical protection, food, lodging and medicine. Trained in warefare, they were able to use force of arms if needed. Acclimated to the climate and landscape, they could offer survival assistance and advice, act as guide and escort. The analogy is close to the role "Strider" plays in The Fellowship of the Ring.