Not a lot of decay and bacteria pre-flood? I have no idea just throwing out there!
Regards, GBTG
In a perfect ecosystem you would still have plant death and decay. But animal and human longevity and vitality might also mean that bacteria were more easily handled.
Various bible based views have been expressed about the antediluvean world.
1) That there was a water vapour canopy around the earth. Since water vapour is a greenhouse gas this would have meant a warmer earth and also more moderated extremes of temperature between day and night and cold and temperate regions. Indeed Artic oil is testimony to polar plant growth in the preflood era.
2) watering of plants etc was managed differently. There was no rain ( before the flood and the rainbow that followed it) but water came from springs and morning dew. It seems there were no clouds before the flood clouds darkened the earth and stars and sun and moon more clearly demarcated the day and night.
3) people were vegetarians. The post flood allowance of meat eating was a response to a world laid waste by the flood in which plants were no longer sufficient for food. The lush plant diversity of the preflood world was gone forever. Much like comparing the Amazon rainforest to overfarmed dust bowl land. The world became a more brutal place with predators and prey.
4) it is possible that the earth had a stronger magnetic field in the past that would have deflected more harmful radiation from the sun. Thus lacking clouds the earth had more light but less harmful radiation. With the greenhouse effect of the water vapour canopy the earth may also have been warmer and indeed polar ice may not have existed.
5) the Hebrew calendar like many ancient calendars was of 360 days corresponding with 12 cycles of the moon. It is possible that seasons were less obvious in a pre flood world where the world was cocooned in a water vapour canopy. But so also it is possible that the earths orbit was pushed outwards 5 days by the catastrophic events of the flood that might have included an asteroid strike for instance. The flood thus both stripped away the protective cocoon for earths ecosystem and our DNA exposing us to more harmful radiation and was accompanied by a cooling effect of being further away from the sun, having less of a greenhouse effect from the water vapour. Also clouds now meant a localised cooling and occasional darkness that was not present before the flood.
The net effect was an ecosystem that had lost its preflood diversity and vitality. A new world more harmfully exposed to the sun but colder for the loss of the greenhouse effect of the water vapour canopy.