Ritual does not have to be religious. Ritual can be habitual behavior. For example, my morning routine is to wake up, go to the bathroom, eat a banana, go to the gym, come home and shower. I do this almost every day. This is habitual behavior and it leaves behind particular material culture in the way of banana remains and gym clothes.

To use a more ancient example you could look at the settlement of Çatalhöyük in Turkey. It is a very old settlement, one of the earliest large settlements in human history that we have discovered so far. Ian Hodder discovered after excavating the site that building tended to follow a general pattern throughout the site. Not only that, but buildings were built on top of the ruins of previous buildings, sometimes after a lengthy period of no occupation at that spot. Despite that, the newer building was built almost to the exact same dimensions with the exact same internal divisions as the previous house from decades earlier. Why did they do this? Because that's just the way you built a house at Çatalhöyük. It was habitual behavior, or ritual.

But what about things that are religious? Part of it is because sometimes the items are found within burials and burials tend to have religiously related material in them. The other part is that some of these items don't show use-wear indicating it was a tool or some sort. The Young Prince burial from Arene Candide in Italy has two items that intrigued me. They are a pair of elk bones in which a hole is drilled through the center. Besides the drilling marks on the bones, there is not other use-wear to indicate its purpose. So it may have some sort of symbolic value that we are unable to ascertain. It may also have had perishable material attached to it such as feathers that have long since decayed.

So claiming something as religious or ritual does appear to be a default answer for a lot of objects, but those claims are usually made with a substantial amount of evidence to back the researcher's claim. We are long past the days of early archaeology when researchers can make bold claims with little to no proof. Archaeology is a science, after all, and must test models and present evidence like other sciences do.

Going beyond what Mictlantecuhtli already said, the ways we separate the world into nice little bundles of information comes from a modernist tradition of what Bruno Latour calls a process of purification. In his book “ We have never been modern”, Latour argues that despite our best attempts to purify our world into perfectly bundled categories, the world is inhabited by hybrids. What is this means in terms of your question? The point is that, as Mictlantecuhtli already pointed out, the anthropological category for religion is far more encompassing that the popular use of the word to solely refer to a condition of believing in a divine being. When religion or ritual are invoked as explanation, more often than not what is actually in mind is the ontological differences between systems of thought. In this sense, what anthropologists refer to as ontology is the multiplicity of forms of social constructions of reality enacted in concrete practices. In this way, religion is more than just the divine; it is the different ways to understand and conceptualize reality.

Now, when dealing with the archaeological record, the “enacted concrete practices” part of the definition of ontology must be emphasized because we cannot shed light on what people from the past actually believed, (nor in the presence for that matter because people lie or because intrinsic problems with consciousness like the problem of qualia). So, the only way to bypass said problem, is by looking at the materials left behind from specific patterned activities, or what Bourdieu calls the habitual. These recurrent practices are shaped and shape social institutions creating the archaeological record. So, when some says that religion is the interpretative tool to analyze “something”, what is being postulated is that religion as a social institution that affords and constraints specific behavior informed by a way of understanding reality is the analytical tool to understand the said “something”. I hope this makes sense.