The tournament is Australia's first World Cup of any kind since 2011 not to feature any of their "big three" quicks in Pat Cummins (back injury), Josh Hazlewood (hamstring, achilles tendon) and Mitch Starc (retirement).
None of Australia's frontline replacements took wickets as Zimbabwe posted 2-169 after being sent in on Friday in Colombo.
Allrounders Marcus Stoinis (1-17) and Cameron Green (1-6) had rare breakthroughs, while Nathan Ellis (0-34) toiled hard at the death without wickets to show for it.
Called in for Xavier Bartlett, quick Ben Dwarshuis (0-40) proved particularly expensive from his four overs.
Even chances were hard to come by, with Matthew Kuhnemann spilling Brian Bennett in the deep for the only major missed opportunity.
Zimbabwe's bowlers had no issues finding scalps, though, as Blessing Muzarabani (4-17) posted career-best figures to roll the highly-fancied Australians for 146.
Brad Evans (3-23) also had his second three-wicket haul of the tournament to help Zimbabwe make inroads into their rivals' top order.
Australia had the option to call in a replacement for Hazlewood when the veteran right-armer was ruled out of the tournament last week.
But travelling reserve Sean Abbott has not yet formally been added to the squad, with Steve Smith also a chance to fill the last remaining spot should Australia apply to the ICC.
Renshaw (65 runs) was one of only two Australian batters to pass 20 runs and said the depleted bowling attack was not the reason his side lost.
"The bowlers in the group that are here are good enough. You've seen them perform so many times in world cricket," he said.
"Sometimes they just don't get the wickets, the ball lands in the gap. But yeah, I back our bowling group.Â
"We probably should have chased that down. I don't think it's the bowling group that should get the blame today."
Renshaw lamented being unable to turn a promising 77-run fifth wicket stand with Glenn Maxwell (31) into a game-winning partnership in the pursuit of 170 for victory.
"That partnership was obviously important but we couldn't get enough momentum in there to chase that down," he said.
"It was just too many to knock."
Renshaw was unsure about the extent of Stoinis's hand injury after Ryan Burl played a shot back to the allrounder.
Stoinis immediately left the field for medical attention but returned to bat, albeit at No.7 rather than No.5 where he had been listed.
"We don't know how bad it is, I'm sure the medical staff will treat that," Renshaw said.
25°C