WASHINGTON—The number of Americans filing new applications for unemployment benefits fell slightly last week as the labor market continued to tread water, but a drop in new COVID-19 cases has raised cautious optimism that momentum could pick up by the spring. The weekly unemployment claims report from the Labor Department on Feb. 11, the most timely data on the economy’s health, also highlighted labor market scarring, with at least 20.4 million people on unemployment benefits in late January. “Claims remain stuck at painfully high levels,” said Robert Frick, corporate economist at Navy Federal Credit Union in Vienna, Virginia. “But we are seeing hopeful signs that claims will begin meaningful declines in the next month or two.” Initial claims for state unemployment benefits slipped 19,000 to a seasonally adjusted 793,000 for the week ending Feb. 6. Data for the prior week was revised to show 33,000 more claims received than previously …