We know for a fact that there was never a global flood. If you' like to know that as well, you'd need to study the science.
It's very likely the abiogenesis paradigm (chemical evolution from elements to organisms) How about Googling it yourself to see what is proposed and what is already known? Your education is your responsibility.
Apart from being incorrect, that's an interesting objection coming from a creationist. That's a valid objection concerning creationism or the flood coming from a naturalist - you have no evidence, just speculation - but it seems irrational coming from a person whose own beliefs are unevidenced speculation or worse (contradicted by evidence).
This time, I'll give you a thorough answer, one I can only give because I did the necessary studying. That's the way to learn.
It's a lunisolar calendar like the Chinese calendar. The lunar part is that the months are all 29- and 30-day months, six of each in a regular year, making the average month 29.5 days - about the time from new moon to new moon. But that only gives us a 354-day year like the Muslim calendar, which is a lunar calendar. As a result, Muslim holidays come about 11 days earlier every year. Ramadan was a winter holiday in 1998 (it began close to the winter solstice) but fell in mid-August by 2011. To prevent this kind of drifting that results from 354-day years year after year, the Hebrews inserted a leap month approximately every three years to keep spring holidays like Passover in the spring.
The Hebrew calendar is based on the Metonic cycle, a 19-year period that takes advantage of the fact that there are almost exactly 235 moons in 19 solar years, and so there are 235 lunar (or synodic) months in 19 solar (or tropical) years. To avoid the constant drifting of the holidays ever earlier in the year that occurs in the lunar Islamic calendar, the Hebrews introduced the intercalary thirteenth leap month in years 3, 6, 8, 11, 14, 17, and 19 of the nineteen-year Metonic cycle.
The synodic month, or one complete cycle of the phases of the Moon from new moon to new moon as seen from Earth, averages 29.530588 mean solar days in length, so 235 of these months equals about 6939.68818 days. The mean tropical year - from winter solstice to winter solstice - is about 365.242199 days, so 19 of these equals about 6939.601781 days. Those numbers are extremely close to one another. This fact is used to keep the Hebrew calendar from drifting too much. Nineteen twelve-month years of about 29.5 days each is only 228 moons, so to make it 235 full moons, seven of those nineteen years get a 30-day leap month. The Hebrews introduced the intercalary thirteenth leap month in years 3, 6, 8, 11, 14, 17, and 19 of the nineteen-year Metonic cycle. In those years, the month of Adar comes twice and are called Adar I and Adar II, the first a 30-day (leap) month and the second a 29-day month.
Using the Metonic cycle and 29- and 30-day months is what makes that calendar lunisolar. It's months are based in the lunar cycle, but the way they are arranged is based in the tropical year and the fact that 19 of the latter are very close to 235 of the former. Unfortunately, the holidays jump all over the Western (Gregorian) calendar, but they stay within the same season, and every nineteen years, come back to the same calendar date.
Rosh Hashanah begins on Tishri 1 of the Hebrew calendar. This date during the years 2003-05 fell on September 27th, September 16th and October 4th. By 2023, Rosh Hashanah fell on September 16th, again as it did 19 years earlier in 2004 (one Metonic cycle).
The reason the years are in the 5000s is because this calendar has been in use since about 3760 BCE. This year is 5784 on the Hebrew calendar (2024 + 3760 = 5784).
Our calendar, the Gregorian calendar is neither a lunar calendar like the Islamic one nor a lunisolar calendar like the Hebrew one, both of which alternate 29- and 30-day months. Our calendar is a solar calendar and uses seven 31-day months, four 30-day months and a 28- or 29-day month, making all years 365 or 366-day years, and keeps dates like the winter solstice fairly rigidly around December 21st +/- a day. The last two solstices were Dec 21, 2022, 3:47 PM and Dec 21, 2023, 9:27 PM. The next one will be Dec 21, 2024, 3:19 AM.
Bonus question: Why does Easter flit about the calendar like Rosh Hashanah? Answer: Easter's date is based in part on the phases of the moon. Easter is the first Sunday after the first full moon after the vernal equinox (March 21). The vernal equinox part keeps it in spring, but introducing phases of the moon into fixing its calendar date makes it vary between March 22 and April 25. If the moon is full on March 21st later in the day than the vernal equinox, and that day is a Saturday, the next day is Easter. Or, if the full moon was a day or a few hours before the equinox, the first full moon after it - almost a month later - will be April 19th, and if that day is a Monday, then Easter is six days after that. April 25th.
I'm sure that this was more answer than you were looking for, but I felt like writing it out (hopefully, a few will find this interesting and informative) inasmuch as I have recently been reviewing the history of the leap day (
bissextus if you want a fancy name for it), which is found in solar calendars unlike the leap month in the lunisolar calendars. Lunar calendars like the Islamic one don't have leap days or months.