The god artifacts exist to create planes and were eventually largely phased out, Gielinor's core doesn't appear to match that. Given OSRS gold is nature it appears to only be a huge amount of anima so that I would sooner suspect that this is the"main course" if you may. The world that will be feasted upon by the god's children's yummy anima that's the yok. However I really could believe so as to create its guardian Telos, they used the template together with the heart.
It simply appears the desert includes a LOT of things BUT Tumeken who are religions or god-like things based on things that are present. Elidnis and the river, Amascut and cats, Icythlarin and puppies, Scabaras and Scarabs, Crondis and Crocodiles and as you pointed out Telos and the heart is another one that is possible. Heck even Amascut created 3 corruptive spirits employing the sight, voice, and hearing Apmeken and went.
That reminds me there is another constant theme where it seems like that the beings are connected and cause a feedback impact. The center and telos, Elidnis and the river, all the desert monkeys dropped one of the senses when Apmeken did, the crocodiles became greedy when Crondis did, and when Het was lost humans started to have health. So here is my theory.
The template is a classic artifact that may use more or 1 to generate new things/beings. The template would be for carrying the individual elements of things they wanted and combining them to make something with the possessions of both 36, where the mirror was for replicating things throughout world creation.
The template has been used by someone Tumeken but I am skeptical, to create Elidnis. Maybe nobody used it even perhaps the artifact just was running and made its own thing. When Tumeken fulfilled with Elidnis he discovered and gained control of this template. Both wanted kids so they used a part of a dog, a cat, and these in the template to create Amascut and Icythlarin. These beings thus possessed some god-like electricity but also traits of the animals they were established in.
After on for reasons not entirely known to us his essence was utilized by Tumeken with all the template and 4 additional animals. Scarabs Monkeys to create this desert pantheon's 4 gods, and Humans. Their poorer lesser children were permitted to stay and Elidnis was banished by Guthix, although afterwards Tumeken blew himself. The lesser gods foiled her plans so she needed to do something although amascut seized her chance to attempt to bring war and destruction to Cheap RS gold the desert.