Amazon by itself is bringing in thousands of people per year, none at the minimum wage. To attribute a good economy in Seattle to a minimum wage is a non-sequitur.
I find it curious though how some can think raising pay by fiat will help the poor. If this were really so why would there be a schedule to phase it in slowly over 7 instead of immediately? I think part of the reason is that it is expected for natural monetary inflation to cancel out the effect of the min wage increase. If we assume 2% target inflation from the FED then that would be a 15% reduction in buying power of the dollar, reducing the burden on businesses for the increase in wage price.
With phased-in increases we tend to see effects that are within the error of margin. Naturally if there was an overnight price increase on anything there would be immediate measurable ramifications, which is probably why the phase-ins are always slow. If people truly thought the effects were positive then they would push for the changes to be as immediate as possible to leave no room for doubt about the effect of the policy.
Meanwhile the homeless situation in Seattle is getting progressively worse. With the increase in minimum wage, some people are paid more, but at the expense of some poor people not being able to acquire a job at all. Certainly we could find a better way of handling things.