TLDR;

Taking a lifeless planet and making it long-term suitable for human life is such a complex and difficult task that I am absolutely sure that the Ancient Gods would have included in their project plan a sub-sub-subproject of making sure that they included some nice coal deposits as risk mitigation against improbable but potentially devastating threats.

Your concern is misplaced

The thing is, the Ancient Gods could not have taken a planet like pre-biotic Earth and terraformed it into something resembling modern Earth suitable for sustaining pre-modern human life.

Or maybe they could do it, using absolutely unimaginably advanced technology; but in this case they would have surely spent 0.1% of their effort to produce nicely placed coal and maybe also petroleum deposits. You see, making sure to add some coal and petroleum to the terraformed planet is such a minor task compared to everything else they had to do that they would have certainly done it, if only as insurance against really horrible unforseen circumstances.

• Pre-biotic Earth had enormous amounts of carbon dioxide in the atmosphere.

  Once upon a time, all that coal and all that petroleum we enjoy were carbon dioxide in the atmosphere. It took life hundreds of millions of years to convert the carbon dioxide in the air into coal and petroleum.

• Pre-biotic Earth had no soil for plants to grow in.

  Soil is entirely a product of life. Without life there is only barren sand at best. Modern Earth has maybe 2 trillion tonnes of coal: compare with about 700 trillion tonnes of soil. I cannot believe that the Ancient Gods expended the effort to make 700 trillion tonnes of soil and did not bother to expend 0.3% of that effort to make some coal to be available in case of dire necessity.

  ^{And by soil I mean everything that's in it, including earthworms and most importantly the nitrogen-fixing bacteria and fungi without which plants cannot survive.}

• Pre-biotic Earth had no oxygen for the humans and other animals to breathe.

  On Earth, photosynthetic life spent billions of years making oxygen from water and carbon dioxide, only for it to be promptly consumed to oxidize everything that could be oxidized. Notably, all those nice iron ore deposits we use were once upon a time elemental iron... Only after spending billions of years making oxygen to oxidize everything that could be oxidized could photosynthetic life even begin to accumulate oxygen in the air and in the ocean.

  The point is that it was not nearly enough for the Ancient Gods to make the 1.2 trillion tonnes of oxygen we currently have in the air, because it would have been gone in a very short time. Oxygen is a very reactive gas, and it will promptly find something to oxidize. They must have first made enormous amounts of oxygen for it to oxidize everything that could be oxidized on the planet, and only after that could they begin making the oxygen in the air.

  Oh, and in order for the planet to maintain free oxygen in the air the planet must be teeming with photosynthetic life. Oxygen is really a very reactive gas; without a constant supply it just won't stay as free oxygen.

Long story short, in order for them to convert a lifeless planet into a planet able to sustain human life long-term, the Ancient Gods must have used their unimaginably advanced technology to create the intricately complicated ecosystems which span the world, and the environmental conditions into which those ecosystems fit. Compared to this, the task of creating some well-placed coal deposits as insurance against cataclysms which might force society into the Bronze Age is so trivial that I'm sure their project manager included it as a cheap risk-mitigation measure.

Food for thought

Smelting metal ores, be they tin and copper ores for the Bronze Age, or iron ores for the Iron Age, needs carbon. Metal ores are metal oxides; you heat up the metal oxide in a carbon-rich environment, the carbon is more reactive than the metal and combines with the oxygen in the ore, and the elemental metal is released.

In the ancient world they used charcoal made from wood to smelt their ores into metals. This is not sustainable. Without access to coal deposits, the world would not have been able to reach the technological level of the Early Modern period before running out of forests. The Industrial Revolution is not even on the horizon.