There are zero airlines offering flights to Singapore. The most direct route isn’t necessarily the cheapest – being flexible is key to finding the lowest airfare rates. For example, try searching by month to see the best time of the week to fly.
Singapore Changi International Airport is just one of the airports in Singapore. If you're not set on a specific airport, try changing your search from Singapore Changi International Airport to Singapore to see a broader range of flights – they might be cheaper.
If you're planning on going to Singapore during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.