What else do you propose?
Because I know of only 2 kinds of "decision makers".
The first are biological entities and the second are devices made by biological entities.
If you are going to propose a third, I'm going to require you to demonstrate the existence of such.
Working on this....
First.... decision-making (human and all other) develops from -is actually composed of -is an arrangement of -most simple interaction.
Most-simple interaction can be likened to a most-simple logic gate.
If happens =yes... if not happen =no
The composition of the simple mechanism is important -but not as important as its logical function.
The basis -the mechanism -remains as it is and imparts basic characteristics -but the arrangement of such simple logic gates allows for all else in an inevitable step-by-step process (until the otherwise-inevitable may be changed by true conscious decision).
If everything which is complex must be composed of the less complex -but also the least complex -then we have a logical basis for understanding the basis of reality.
We also know that something drives the simple to become arranged in complex ways.
From simplicity, decision-making
essentially always existed -and became more complex -with increasing capabilities and features.
For example... evolution -DNA, etc. is both a designer and an intelligent one by one definition -but, due to its arrangement, it lacks what we would call self-awareness.
However, it actually has the basis of self-awareness.... which is also most basic interaction (reaction as awareness of action).
It is just that.... considering evolution as separate from all else (which it actually can not be), its self-awareness is less developed than other aspects.
Design, intelligence and self-awareness all existed as most-simple things -as the most simple thing/s -then became more complex -with the various aspects augmented or diminished in relation to each other in various locations within the overall arrangement.
Everything is OF a design -and by that design increased the complexity of its own design until it produced that which could do things BY what we would call conscious decision and design.
That increasing complexity IS increasing intelligence/arrangement of logic gates.
Awareness and self-awareness in a complex sense are by arrangements of those gates (reaction as awareness of action) into a capable processor.
One very important step in conscious design is separation of self and environment -even though self is technically part of environment.
The border being between the processor/sensor/interface ( "I" ) and that which is external to the processor, etc.
The processor/designer requires memory, sensors, interface mechanisms and a process which allows sensed external or internal states residing in memory to be accessed, altered according to remembered knowledge thereof being rearranged, and then applied by interface mechanisms to the external
.
Only thereby can the otherwise-inevitable and -predictable be changed.
Understanding/knowledge of self/existence of self would lead to and
allow for decisions based on that realization -and design of an external environment -suited to the logically-developing needs of the self.
Self and environment would then develop together in tandem -from simple to complex -but BY design rather then simply being OF a design.
Nature can only self-design to a certain point -which is apparently the development of "self" and simple environment (most complex environment possible by nature alone) -then the processor is required for all else.
Our disagreement seems to be about that point -whether it was necessarily before or after the initiation of the physical universe. I don't see that such required atoms and DNA specifically to develop first -as things essentially always existed which could perform similar logical functions as our brains/minds. The question is whether atoms and DNA required conscious design -and are indicative thereof.
An extremely complex environment alone -especially one which meets the specific needs of a psychology -developing in the absence of a capable processor/psychology -is not logical.
I will try to specifically address the reason humans or similar (DNA-based) would not be the first decision-makers later.